We will use a newly developed high throughput sensitive, quantitative proteomic approach to detect key proteins and signaling pathways that are oxidatively damaged during aging and Alzheimer's disease (AD). We will accurately identify the initial targets of age- and ABeta-mediated oxidative stress and their association with neuropathology. This addresses several key elements of this RFA as both normal brain aging and AD are associated with free radical-mediated damage and a loss of synaptic function. which may be a primary cause of cognitive impairments. Many age-related oxidative stress-mediated processes are attenuated by Caloric Restriction (CR). We have recently demonstarted that CR also reduces ABeta deposition and glial activation in the bigenic mutated presenilin & amyloid precursor protein (PS1+APP) mouse models of AD. In addition, using liquid chromatography-mass spectrmetry proteomic methodology, we discovered that certain proteins associated with learning and memory (e.g., NMDA/AMPA receptor, fyn, CaMKII) are oxidatively damaged in the PS1+APP mouse. Therefore, we propose to identify key proteins and signaling pathways involved in free radical mediated syanptic dysfuntion during normal aging and AD using our sensitive and accurate proteomic approach in the PS1+APP mouse. Since CR attenuates many age-related oxidative stress mediated processes, we will determine which proteins and pathways are protected by this dietary intervention. 1: We will use quantitative proteomics to determine the initial targets of free radicals in PSI+APP transgenic and nontransgenic mice to establish the functional links between neuropathological changes and oxidative modification of key synaptic signaling proteins. 2: We will identify the phosphorylation alterations in cell signaling pathways that mediate synaptic dysfunction during aging and Abeta-mediated pathology. 3: We will perform statistical validation of protein identifications from database searches and we will use bioinformatcis to integrate our proteomic data into signaling pathways to identify the underlying mechanisms involved in synaptic dysfunction in the PS1+APP mouse model.